JP2562573B2 - Back tension device of three-point support type pile driver. - Google Patents

Description

The present invention relates to a back tension device for a three-point support type pile driver.

[Conventional technology]

As shown in FIG. 3, in the three-point support type pile driver 1, a front bracket 3 is attached to a front portion of a main body 2, a lower portion of a leader 4 is pivotally supported on the front bracket 3, and an upper portion of the leader 4 is attached. It is supported by the main body 2 by two back stays 5. The wire rope 7 for the auger fed from the winch drum of the main body 2 through the pulley 6 is included in the sheave 9 of the top sheave block 8 fixed to the upper end of the leader 4 and the sheave 12 of the auger 11 equipped with the screw 10. The end 7a is pivotally attached to the top sheave block 8 by hanging.

Further, the three-point support type pile driver 1 is shown in FIGS. 4 (A) and (B).
As shown in, suspend the auger 11 and the hammer 13 on the leader 4,
Rotate the reader 4 by about 90 degrees with a rotating device (not shown),
A double-sided rotary type in which a pile is driven by using both the auger 11 and the hammer 13, and as shown in FIGS. 5A and 5B, the auger 11 or the hammer 13 or the drove auger (not shown) is provided on the front surface of the reader 4. ) And the like, in which end faces are fixed and the piles are driven, the work is usually performed on the front side of the main body 2.

The pile driving work, particularly the auger work, is restricted by the auger work because a large force is applied to the leader 4 at the time of excavating the screw during excavation and a great force at the time of pulling out the screw after the excavation, and acts as bending stress on the leader 4.

To solve this, if bending stress is generated in advance from the center of the leader 4 to the opposite side of the auger 11, the leader 4
Bending stresses on the auger can be reduced to increase auger work capability.

The device used for this is a back tension device, and there are various devices. For example, as disclosed in Japanese Utility Model Application Laid-Open No. 57-96235, a back tension rope whose one end is fixed to a front bracket is used as a rotary leader. After passing the sheave of the top sheave block installed on the top of the, connect the other end to the rod of the double-acting hydraulic cylinder supported on the front bracket, insert the solenoid switching valve into the operating circuit of the double-acting hydraulic cylinder, and There is a configuration in which the electromagnetic switching valve is switched according to the rotation so that the rope is stretched for auger work and the rope is loosened for hammer work.

[Problems to be Solved by the Invention]

However, the above device only replaces the conventionally used turnbuckle with a double-acting hydraulic cylinder and makes it easier to operate.To correct the looseness of the back tension wire rope during auger work, It is necessary to insert a manual switching valve in series in the operation circuit of the hydraulic cylinder upstream of the electromagnetic switching valve and operate the manual switching valve each time to correct the rope tension. Since this correction is frequently performed during the auger work, it is very troublesome for the driver to operate it, and further, it causes damage to the reader due to an erroneous operation, so improvement has been desired.

The present invention has been made in view of the above point, and eliminates the troublesomeness of manually correcting the tension of the tension rope and the risk of erroneous operation, and the back tension of the three-point support type pile driver having high operability and safety. The purpose is to provide a device.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention connects one end of a wire rope for back tension to the auger rear side of a top sheave block fixed to the leader upper end of a three-point support type pile driver, and connects the other end to the other end. It is connected to a front bracket that supports the leader via a single-acting hydraulic cylinder, and a constant pressure is constantly applied to the head side of the single-acting hydraulic cylinder,
It is characterized in that the tension of the back tension wire rope is kept constant.

[Work]

Therefore, backward bending stress is always applied to the leader with a constant tension.

〔Example〕

An embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. In the figure, the same reference numerals as those in FIGS. 3 to 5 indicate the same elements.

As shown in FIG. 1, the leader 4 has a front bracket 3
The lower part of the sheave 9 is pivotally supported by the lower part, and the top sheave block 8 is fixedly mounted on the upper part of the upper sheave block. Being pivoted.

A bracket 21 is fixedly provided on the rear side of the auger of the top sheave block 8, one end of a wire rope 22 for back tension is connected to the bracket 21 by a pin 23, and the other end is pivotally supported by a pin 24 on the front bracket 3. It is connected to the rod 26 of the single-acting hydraulic cylinder 25 with a pin 27.

Then, as shown in FIG. 2, the single-acting hydraulic cylinder 25
Has its head side 25a connected to a hydraulic pump 29 via an electromagnetic switching valve 28, and a relief valve 30 is connected to the hydraulic pump 29 in parallel with the electromagnetic switching valve 28 so that the single-acting hydraulic cylinder 25 is constantly fixed. The wire rope 22 for back tension is stretched by applying pressure. The solenoid 28a of the electromagnetic switching valve 28 is connected to the power source 32 via the on / off switching switch 31.

With the above configuration, when the on / off switch 31 is turned on, oil is sent to the head side 25a of the single-acting hydraulic cylinder 25 via the electromagnetic switching valve 28, and the single-acting hydraulic cylinder 25 reduces the rod 26. Then, a constant pressure equal to the set pressure of the relief valve 30 is constantly applied, and the back tension wire rope 22 is constantly pulled by the set pressure of the relief valve 30 to keep the tension constant, and to this constant set pressure. Continue to apply corresponding bending stress to the leader 4.

Therefore, the trouble and erroneous operation of correcting the wire rope for back tension by the conventional manual operation are eliminated,
Operability and safety are improved, and auger work can be performed smoothly.

The hydraulic pressure supplied to the single-acting hydraulic cylinder 25 can be easily ensured by branching from the low-pressure hydraulic source that is constantly raised for use in operating the pile driver 1.

〔The invention's effect〕

As described above, the present invention, on the auger rear side of the top sheave block fixed to the leader upper end of the three-point support type pile driver,
One end of the wire rope for back tension is connected, the other end is connected to a front bracket that supports the leader via a single-acting hydraulic cylinder, and a constant pressure is constantly applied to the head side of the single-acting hydraulic cylinder, Since the tension of the wire rope for back tension is kept constant, a backward bending stress always acts on the leader with a constant pressure, and even if a load is applied to the front side during auger work, the wire for back tension is Due to the constant tension of the rope, operability and safety are improved and auger work can be performed smoothly without any manual operation.

[Brief description of drawings]

FIG. 1 is a schematic view of a leader pulling device according to the present invention, FIG. 2 is a hydraulic / electric circuit diagram showing an embodiment in which a constant pressure is constantly applied to a single-acting hydraulic cylinder, and FIG. The front view of the support type pile driver and FIGS. 4 (A) and 4 (B) are for explaining the working position of the double-sided rotary reader.
Is an explanatory view when an auger is used, (B) is an explanatory view when a hammer is used, and FIGS. 5 (A) and 5 (B) are for explaining the working position of the end face fixed type reader. (A)
[Fig. 3] is an explanatory view when an auger is provided, and (B) is an explanatory view when a hammer or drop auger is provided. 1 ... Three-point support type pile driver, 2 ... Main body, 3 ... Front bracket, 4 ... Leader, 5 ... Back stay, 6 ...
… Pulley, 7… Wire rope for auger, 7a… Rope 7
End, 8 …… top sheave block, 9 …… sheave, 10 …… screw, 11 …… auger, 12 …… auger 11 sheave, 13 …… hammer, 21 …… bracket, 22 …… back tension wire Rope, 23,24 ... pin, 25 ...
Single-acting hydraulic cylinder, 25a ... Head side of single-acting hydraulic cylinder 25, 26 ... Rod, 27 ... Pin, 28 ... Electromagnetic switching valve,
28a ... solenoid, 29 ... hydraulic pump, 30 ... relief valve, 31 ... on / off switch, 32 ... power supply

Claims (1)

(57) [Claims] 1. A back tension wire rope is connected to one end of a back sheave block of a top sheave block fixed to the upper end of a leader of a three-point support type pile driver, and the other end is connected via a single-acting hydraulic cylinder. It is configured such that it is connected to a front bracket that supports a leader, and a constant pressure is constantly applied to the head side of the single-acting hydraulic cylinder to keep the tension of the back tension wire rope constant. Back tension device for point-supported pile driver.